[PATCH 27/29] drm/i915/gt: Declare when we enabled timeslicing

[Chris Wilson]

Let userspace know if they can trust timeslicing by including it as part
of the I915_PARAM_HAS_SCHEDULER::I915_SCHEDULER_CAP_TIMESLICING

v2: Only declare timeslicing if we can safely preempt userspace.

Fixes: 8ee36e048c98 ("drm/i915/execlists: Minimalistic timeslicing")
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/gt/intel_engine_user.c | 27 +++++++++++++++------
 include/uapi/drm/i915_drm.h                 |  1 +
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_user.c b/drivers/gpu/drm/i915/gt/intel_engine_user.c
index 64eccdf32a22..80b87c466724 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_user.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_user.c
@@ -90,13 +90,17 @@ static void sort_engines(struct drm_i915_private *i915,
 static void set_scheduler_caps(struct drm_i915_private *i915)
 {
 	static const struct {
-		u8 engine;
-		u8 sched;
-	} map[] = {
+		u8 flag;
+		u8 cap;
+	} engine_map[] = {
 #define MAP(x, y) { ilog2(I915_ENGINE_##x), ilog2(I915_SCHEDULER_CAP_##y) }
 		MAP(HAS_PREEMPTION, PREEMPTION),
 		MAP(HAS_SEMAPHORES, SEMAPHORES),
 		MAP(SUPPORTS_STATS, ENGINE_BUSY_STATS),
+#undef MAP
+	}, sched_map[] = {
+#define MAP(x, y) { ilog2(I915_SCHED_##x), ilog2(I915_SCHEDULER_CAP_##y) }
+		MAP(HAS_TIMESLICES_BIT, TIMESLICING),
 #undef MAP
 	};
 	struct intel_engine_cs *engine;
@@ -105,6 +109,8 @@ static void set_scheduler_caps(struct drm_i915_private *i915)
 	enabled = 0;
 	disabled = 0;
 	for_each_uabi_engine(engine, i915) { /* all engines must agree! */
+		struct i915_sched_engine *se =
+			intel_engine_get_scheduler(engine);
 		int i;
 
 		if (intel_engine_has_scheduler(engine))
@@ -114,11 +120,18 @@ static void set_scheduler_caps(struct drm_i915_private *i915)
 			disabled |= (I915_SCHEDULER_CAP_ENABLED |
 				     I915_SCHEDULER_CAP_PRIORITY);
 
-		for (i = 0; i < ARRAY_SIZE(map); i++) {
-			if (engine->flags & BIT(map[i].engine))
-				enabled |= BIT(map[i].sched);
+		for (i = 0; i < ARRAY_SIZE(engine_map); i++) {
+			if (engine->flags & BIT(engine_map[i].flag))
+				enabled |= BIT(engine_map[i].cap);
 			else
-				disabled |= BIT(map[i].sched);
+				disabled |= BIT(engine_map[i].cap);
+		}
+
+		for (i = 0; i < ARRAY_SIZE(sched_map); i++) {
+			if (se->flags & BIT(sched_map[i].flag))
+				enabled |= BIT(sched_map[i].cap);
+			else
+				disabled |= BIT(sched_map[i].cap);
 		}
 	}
 
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 1987e2ea79a3..cda0f391d965 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -524,6 +524,7 @@ typedef struct drm_i915_irq_wait {
 #define   I915_SCHEDULER_CAP_PREEMPTION	(1ul << 2)
 #define   I915_SCHEDULER_CAP_SEMAPHORES	(1ul << 3)
 #define   I915_SCHEDULER_CAP_ENGINE_BUSY_STATS	(1ul << 4)
+#define   I915_SCHEDULER_CAP_TIMESLICING	(1ul << 5)
 
 #define I915_PARAM_HUC_STATUS		 42
 
-- 
2.20.1